JP6462564B2 - Switch device - Google Patents

Description

  The present invention relates to an optical signal switch device, and more particularly to a switch device used for branching and inserting optical signals in wavelength division multiplexing transmission.

  In recent years, ROADM (Reconfigurable Optical Add / Drop Multiplexer) technology has been devised to increase the speed and capacity of optical communications. In an optical network based on ROADM, a wavelength division multiplexing transmission system is used, and an optical signal having an arbitrary wavelength can be branched and inserted without being converted into an electric signal. In addition, in an optical network based on ROADM, when a route through which an optical signal of each wavelength passes should be changed, newly established, or abolished, the route can be changed, that is, reconfigured without performing work such as connection work. (Reconfigurable).

  In order to realize ROADM, a switch device (also referred to as a multicast switch) that can input and output a plurality of wavelengths and can change a route is required. That is, a switch device used in ROADM has a function of receiving an optical signal input from a client device and inserting it into a route of the ROADM network, and a function of outputting an optical signal branched from the route of the ROADM network to the client device. The path through which the optical signal passes can be changed dynamically.

  FIG. 9 is a top view of an example of the switch device 900 used in ROADM. The switch device 900 has two configurations in which the number of routes (number of routes) on the ROADM network side is 8, and the number of routes (number of wavelengths) on the client device side is 16. The switch device 900 includes two splitter units 920 and eight switch units 930 in a housing 960. Each splitter unit 920 has a predetermined number of optical splitters, and each switch unit 930 has a predetermined number of optical switches. One end of the splitter unit 920 is connected to the ROADM network via the network-side fiber 940, and the other end is branched and connected to one end of the switch unit 930. Further, the other end of the switch unit 930 is connected to the client device via the client side fiber 950. In FIG. 1, the wiring among the splitter unit 920, the switch unit 930, the network side fiber 940, and the client side fiber 950 is not shown for simplification. With such a configuration, an optical signal can be branched and inserted between the ROADM network and the client device.

  By changing the number of splitter units 920 and switch units 930 included in the switch device 900, and the number of branches of the optical splitter included in the splitter unit 920 and the optical switch included in the switch unit 930, the desired number of paths and wavelengths can be changed. You can get a number.

  In the switch apparatus 900 shown in FIG. 9, in order to increase the corresponding number of wavelengths, it is necessary to increase the number of switch units 930. If it does so, the area required for arrangement | positioning of the switch apparatus 900 will increase, and manufacturing cost will increase by the increase in the material required for manufacture. In order to cope with a larger number of wavelengths, downsizing and cost reduction of the switch device are required.

  The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a switch unit that can reduce the area required for arrangement and reduce the manufacturing cost, and a switch device including the switch unit. And

One aspect of the present invention is a switch unit for selecting and outputting a path of an input optical signal, the substrate, one common port for inputting and outputting the optical signal, and the optical signal A plurality of branch ports for performing input / output of a plurality of signals, a plurality of waveguides connecting the common ports and the branch ports, and a plurality of Mach-Zehnder interferometers (MZI) provided on the waveguides. And first and second optical switch arrays each including an optical switch extending along the surface of the substrate, wherein the first and second optical switch arrays are arranged from the branch port side to the first and second optical switch arrays. It has a tapered shape towards the common port side, and the branch port of the optical switch included in the first optical switch array and the common of the optical switch included in the second optical switch array Pau DOO so that close, a switch unit, characterized in that said first optical switch array and the second optical switch array is arranged.

  According to the present invention, since the two optical switch arrays are arranged in the opposite direction and in parallel in the switch unit, the area of the switch unit can be reduced and the manufacturing cost can be reduced.

It is a schematic block diagram of the switch apparatus which concerns on one Embodiment of this invention. It is a mimetic diagram of a switch device concerning one embodiment of the present invention. It is a schematic diagram of the optical switch which concerns on one Embodiment of this invention. It is a top view of the switch part concerning one embodiment of the present invention. It is a top view of the switch part concerning one embodiment of the present invention. It is a top view of the switch part concerning one embodiment of the present invention. It is a top view of the switch part concerning one embodiment of the present invention. It is a top view of the switch part concerning one embodiment of the present invention. It is a schematic diagram of the optical switch which concerns on one Embodiment of this invention. It is a figure which shows the adjacent part of MZI which concerns on one Embodiment of this invention. It is a figure which shows the adjacent part of MZI which concerns on one Embodiment of this invention. It is a figure which shows the adjacent part of MZI which concerns on one Embodiment of this invention. It is a top view of the conventional switch apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a switch device 10 according to the present embodiment. The switch device 10 can be connected between a ROADM network having a plurality of routes and a plurality of client devices. Thereby, the switch apparatus 10 can branch an optical signal from a route of the ROADM network to a desired client device, or can insert a signal from the client device to a desired route of the ROADM network.

  The switch device 10 includes two splitter units 20 and four switch units 30. The splitter unit 20 and the switch unit 30 are housed in a housing 60. One end of the splitter unit 20 is connected to the ROADM network via the network-side fiber 40, and the other end is branched and connected to one end of the plurality of switch units 30. Further, the other end of the switch unit 30 is connected to the client device via the client side fiber 50. In FIG. 1, for simplification, the wiring among the splitter unit 20, the switch unit 30, the network side fiber 40, and the client side fiber 50 is not shown.

  FIG. 2 is a schematic diagram showing a wiring method of the switch device 10. The splitter unit 20 includes eight optical splitters 21 on one chip (substrate). The optical splitter 21 used in this embodiment is a 1 × 16 optical splitter, and has one common port 21a at one end and 16 branch ports 21b at the other end. The optical signal input from the common port 21a is divided and output to each branch port 21b. Alternatively, the optical signals input from the branch ports 21b are joined to the common port 21a and output. The splitter unit 20 is manufactured using, for example, a PLC formed on a quartz substrate, and the relative refractive index difference Δ between the core and the clad is about 0.4%. By using such a low relative refractive index difference Δ, connection loss can be reduced.

The switch unit 30 includes eight optical switches 31 provided on a single chip (substrate), and tap couplers 32 connected to the respective optical switches 31. As will be described later, four optical switches 31 are arranged in reverse directions, but are shown in the same direction for convenience in FIG. The optical switch 31 used in this embodiment is a 1 × 8 optical switch, and has one common port 31a at one end and eight branch ports 31b at the other end. The optical signal input from the common port 31a is output to one of the branch ports 31b according to control. Alternatively, the optical signal input from each branch port 31b is output to the common port 31a or discarded without being output depending on the control. The switch unit 30 is manufactured using, for example, a PLC formed on a silicon substrate, and the relative refractive index difference Δ between the core and the clad is about 1.5%. By using such a high relative refractive index difference Δ, the size can be reduced. In order to increase the number of wavelengths supported by the switch device 10, it is necessary to increase the number of optical switches 31 included in each switch unit 30 or increase the number of switch units 30 themselves. Therefore, in order to reduce the arrangement space of the switch device 10, the switch unit 30 is reduced in size by adjusting the switch unit 30 to a high relative refractive index difference Δ.
In general, Ge is used as a dopant for increasing the refractive index of the core, but a dopant capable of increasing the refractive index, such as Zr, may be used instead. Accordingly, the relative refractive index difference Δ between the core and the clad can be increased to about 5% (2.5% to 12%), and the switch unit 30 can be further downsized.

  The tap coupler 32 has one common port at one end and two branch ports at the other end. The common port of the tap coupler 32 is connected to the common port 31a of the optical switch 31, one of the two branch ports of the tap coupler 32 is connected to the client side fiber 50, and the other is connected to the PD (not shown). Has been. The optical output from the optical switch 31 can be monitored using the PD. Although the branching ratio of the tap coupler 32 is arbitrary, in this embodiment, 5% branches to the PD side.

  The branch port 21b of the optical splitter 21 and the branch port 31b of the optical switch 31 include a shuffle fiber array 70 having a plurality of three-dimensionally crossed optical fibers and fiber arrays formed at both ends of the optical fibers. Connected through. In FIG. 2, for simplification, only a part of the optical fibers included in the shuffle fiber array 70 is schematically shown.

  FIG. 3 is a schematic diagram showing the configuration of the optical switch 31. The optical switch 31 has one common port 31a at one end and eight branch ports 31b at the other end. The optical switch 31 has a plurality of Mach-Zehnder interferometers (MZI) 33 connected in cascade.

  The MZI 33 has one or two input ports at one end and one or two output ports at the other end. Since the MZI 33 has no directionality, the term “input port” and “output port” are merely used for distinction, and both can be used for both input and output. Between the input port and the output port of the MZI 33, two couplers (directional couplers in the present embodiment) 33a and 33d and two waveguides 33b and 33c sandwiched between the two couplers are provided. It has been. In addition, a heater 33e as a heating means is provided in the vicinity of at least one of the two waveguides 33b. As a coupler included in the MZI 33, not only a DC (directional coupler) but also a WINC (wavelength independent coupler), a Y branch, or the like may be used depending on characteristics.

  In a state where heating by the heater 33e is not performed, the optical signal input from one of the two input ports of the MZI 33 is adjusted so as to be output from one of the two output ports. When one of the two waveguides 33b and 33c is heated by the heater 33e, the propagation speed of light in the waveguide decreases, and the optical signal changes so as to be output from the other of the two output ports. Therefore, it is possible to select which of the two output ports outputs the signal input from the input port by controlling on / off of the heating of the heater 33e. Each heater 33e is connected to an electrode pad 35a, 35b, which will be described later, by an arbitrary wiring method, and by controlling the presence or absence of power supply to the heater 33e from the control unit (not shown) via the electrode pad 35a, 35b, The presence or absence of heating of the heater 33e can be switched. With such a configuration, the path through which the optical signal passes in the optical switch 31 can be dynamically changed.

  As described above, the optical switch 31 includes a plurality of MZIs 33 connected in cascade. One MZI 33 is provided in the first stage 31c of the optical switch 31 when viewed from the common port 31a side. A tap coupler 32 is connected to one of the two input ports of the MZI 33, and the two MZI 33 input ports of the second stage 31d are connected to the two output ports, respectively. The output ports (total 4) of the two MZIs 33 in the second stage 31d are respectively connected to the input ports of the four MZIs 33 in the third stage 31e. The output ports (total 8) of the four MZIs 33 in the third stage 31e are connected to the gate switch unit 31f. In the gate switch unit 31f, one MZI 33 is connected to one of the two output ports of each MZI 33 in the third stage 31e, and two MZIs 33 are connected in series to the other. The gate switch portion 31f can increase the extinction ratio even when no power is supplied.

  FIG. 4A is a top view of the switch unit 30 according to the present embodiment. The switch unit 30 includes two optical switch arrays 34a and 34b arranged in reverse and in parallel on a single chip (substrate). The optical switch arrays 34a and 34b extend along the surface of the chip, and each has four optical switches 31 arranged in parallel. That is, the four optical switches 31 included in the optical switch arrays 34a and 34b are arranged such that all the common ports 31a are arranged on one side and all the branch ports 31b are arranged on the other side. The common port 31a of each optical switch 31 is connected to a common terminal 34c provided at one end of the optical switch arrays 34a and 34b, and the branch port 31b of each optical switch 31 is provided at the other end of the optical switch arrays 34a and 34b. Connected to the branch terminal 34d. The common terminal 34c of the first optical switch array 34a and the branch terminal 34d of the second optical switch array 34b are provided on the side surface 3c of the switch unit 30, and the branch terminal 34d of the first optical switch array 34a, The common terminal 34c of the second optical switch array 34b is provided on the side surface 3d of the switch unit 30 facing the side surface 3c.

  Note that the number of optical switches 31 included in one optical switch array 34a, 34b is not limited to four, and may be an arbitrary number of one or more. The optical switches 31 included in the optical switch arrays 34a and 34b may not all have the same configuration, and may have different configurations. Furthermore, the first optical switch arrays 34a and 34b may have different configurations.

  Here, it will be specifically described that the first optical switch array 34a and the second optical switch array 34b are arranged in opposite directions and in parallel. The direction from the common terminal 34c of the first optical switch array 34a to the branch terminal 34d is opposite to the direction from the common terminal 34c of the second optical switch array 34b to the branch terminal 34d. The optical switch array 34a and the second optical switch array 34b are arranged. That is, the direction from the common port 31a of each optical switch 31 included in the first optical switch array 34a to the branch port 31b and the branch port from the common port 31a of each optical switch 31 included in the second optical switch array 34b. The direction toward 31b is the opposite direction.

  A large number of waveguides and MZIs 33 are arranged on the branch terminal 34d side of the optical switch arrays 34a and 34b (that is, on the branch port 31b side of the optical switch 31). In order to prevent the heat generated by the heater 33e of a certain MZI 33 from affecting the operation of the other MZI 33, it is necessary to arrange the MZIs 33 apart from each other by a predetermined distance. On the other hand, a small number of waveguides and MZIs 33 are arranged on the common terminal 34c side of the optical switch arrays 34a and 34b (that is, on the common port 31a side of the optical switch 31). Therefore, an extra region where the waveguide and the MZI 33 are not disposed is generated on the common terminal 34c side of the optical switch arrays 34a and 34b.

  As shown in FIG. 4A, the switch unit 30 according to the present embodiment has a tapered shape from the branch terminal 34d to the common terminal 34c, and there is an extra region so that the tip part is sandwiched from both sides. doing. Therefore, the first optical switch array 34a and the second optical switch array 34b are disposed in the opposite directions, and the tip portions are brought close to each other, thereby generating on the common terminal 34c side of the optical switch arrays 34a and 34b. Excess areas overlap each other. As a result, the second optical switch array 34b is disposed in an extra region on the common terminal 34c side of the first optical switch array 34a, and the first optical region is disposed in an extra region on the common terminal 34c side of the second optical switch array 34b. The optical switch array 34a is arranged. With such a configuration, by arranging the switch arrays 34a and 34b in a portion that has conventionally been an extra region, the size of the switch unit 30 can be reduced, and the manufacturing cost can be reduced.

  Furthermore, in the switch unit 30 according to the present embodiment, since the optical switch arrays 34a and 34b are arranged in the reverse direction, the heaters 33e included in the MZI 33 are dispersed without being concentrated on a part of the chip. Therefore, since heat generated when the switch unit 30 is operated is dispersed throughout the chip, heat can be radiated using the radiation fins or the like more efficiently than when heat is concentrated in a part.

  The switch unit 30 has two electrode pads 35a and 35b arranged so as to sandwich the optical switch arrays 34a and 34b along the longitudinal direction of the optical switch arrays 34a and 34b (the direction connecting the common terminal 34c and the branch terminal 34d). Is further provided. The first electrode pad 35a on the first optical switch array 34a side is electrically connected to the first optical switch array 34a, and the second electrode pad 35b on the second optical switch array 34b side is second. The optical switch array 34b is electrically connected. Each electrode pad 35a, 35b is electrically connected to each heater 33e included in each optical switch 31, and serves as a power supply path to the heater 33e. Further, each electrode pad 35 a, 35 b is connected to an electrode outside the switch unit 30.

  In the conventional switch unit, electrode pads are provided on both sides of one optical switch array, and each electrode pad is connected to an external electrode provided on both sides of the switch unit. For this reason, the external electrodes provided on both sides of the switch part have also been a factor in increasing the area required for the arrangement of the switch part. On the other hand, in the switch unit 30 according to this embodiment, electrode pads 35a and 35b are provided on both sides of the two optical switch arrays 34a and 34b, and the respective electrode pads 35a and 35b are connected to external electrodes. That is, only one external electrode is required for one optical switch array. Therefore, since the number of external electrodes required per one optical switch array can be halved as compared with the conventional case, the area required for the arrangement of the switch portions can be further reduced.

  Since the first electrode pad 35a is connected only to the first optical switch array 34a and the second electrode pad 35b is connected only to the second optical switch array 34b, the switch section 30 is connected to the first optical switch array 34b. A split can be made between the array 34a and the second optical switch array 34b. FIG. 4B is a top view of a divided switch unit 30a formed by dividing the switch unit 30 into two parts. The split switch unit 30a is formed by cutting the switch unit 30 of FIG. 4A at the cut surface 3b between the two optical switch arrays 34a and 34b. 4B shows only the configuration on the first optical switch array 34a side, the configuration on the second optical switch array 34b side is the same. By combining two divided switch units 30a having such a configuration and arranging them in the reverse direction, the switch unit 30 can be used as one switch unit 30. Note that the switch unit 30 is not necessarily cut to form the split switch unit 30a, and the split switch unit 30a may be manufactured from the beginning.

  Since the switch unit 30 shown in FIG. 4A includes the optical switch arrays 34a and 34b on one chip, when there is a manufacturing defect in one of the optical switch arrays 34a and 34b, there is no problem. Will be useless. On the other hand, the split switch unit 30a shown in FIG. 4B includes only one optical switch array 34a (or 34b) on one chip, and therefore only the optical switch array 34a (or 34b) in which a failure has occurred. It can be discarded and the yield can be improved.

(Second Embodiment)
In the first embodiment, the size of the switch unit 30 is reduced by disposing the optical switch arrays 34a and 34b in the opposite directions by using an extra region generated on the common terminal 34c side. However, an extra area on the side where the optical switch arrays 34a and 34b are not arranged (on the electrode pads 35a and 35b side) remains unused. In the present embodiment, the area of the switch unit 30 is further reduced by changing the shapes of the optical switch arrays 34a and 34b to more efficiently use the extra area.

  FIG. 5A is a top view of the switch unit 30 according to the present embodiment. The switch unit 30 according to the present embodiment has the same configuration as that of the first embodiment, but the shapes of the optical switch arrays 34a and 34b are different. The optical switch arrays 34a and 34b according to the present embodiment have a substantially right triangle shape. That is, as shown in FIG. 5B, the branch ports 31b (a total of 32) of the four optical switches 31 included in the optical switch arrays 34a and 34b are arranged along the base B of the right triangle A, and the perpendicular C The waveguides of the optical switch arrays 34a and 34b extend in a region between the vertical side D and the hypotenuse D, and a common port 31a of the four optical switches 31 (total) in the vicinity of the apex formed by the vertical side C and the hypotenuse D 4) are located. Similarly to the first embodiment, the first optical switch array 34a and the second optical switch array 34b are arranged in opposite directions.

  In the optical switch arrays 34a and 34b according to the present embodiment, the waveguide and the MZI 33 are brought close to the perpendicular C side of the right triangle A (the side on which the electrode pads 35a and 35b are provided). Therefore, an extra region where the waveguide and the MZI 33 are not arranged is collected on the hypotenuse D side of the right triangle A, and hardly occurs on the side where the electrode pads 35a and 35b are provided. By arranging the first optical switch array 34a and the second optical switch array 34b having such a configuration in an opposite direction and in parallel so as to be located in an extra region of each other, the waveguide and MZI in the switch unit 30 are arranged. Therefore, it is possible to reduce an extra area where no is disposed, and to further reduce the area of the switch unit 30 as compared with the first embodiment.

  As shown in FIG. 4B, the switch unit 30 according to the present embodiment may be divided between the first optical switch array 34a and the second optical switch array 34b to form the divided switch unit 30a.

(Third embodiment)
In the optical switch 31 shown in FIG. 3, when the optical signal input from the branch port 31b is not output to the common port 31a, the control device controls the heater 33e of any MZI 33 to input the input light. The signal is output to an output port 33f (referred to as a dummy output port) that is not connected to the common port 31a. Although not shown in FIG. 3, it is desirable to provide a waveguide (referred to as a dummy waveguide) for guiding an optical signal not output to the common port 31a from the dummy output port 33f to the outside of the switch unit 30. In the present embodiment, a preferable form of the dummy waveguide is defined.

  FIG. 6 is a top view of the switch unit 30 according to the present embodiment. The optical switch arrays 34a and 34b according to the present embodiment have a dummy waveguide 36 that is a collection of waveguides extending from the dummy output port 33f of each MZI 33. A portion of the optical switch array 34a, 34b other than the dummy waveguide 36, that is, a signal waveguide 37 that is a collection of waveguides connecting the branch port 31b and the common port 31a is substantially a right triangle as in the second embodiment. It has a shape. The dummy waveguide 36 is connected to the side surface 3c provided with the common terminal 34c and the branch terminal 34d and the dummy terminal 36a provided on the side surface 3e adjacent to the side surface 3d.

  The width in the direction orthogonal to the longitudinal direction of the switch section 30 (the direction connecting the common terminal 34c and the branch terminal 34d) is the sum of the width in the vicinity of the common terminal 34c and the width in the vicinity of the branch terminal 34d of the optical switch arrays 34a and 34b. Restrained by If the dummy waveguide 36 is connected to the common terminal 34c, many waveguides are arranged in the vicinity of the common terminal 34c, so that the width in the vicinity of the common terminal 34c of the optical switch arrays 34a and 34b is increased. The entire width of the switch unit 30 is increased. On the other hand, in the switch unit 30 according to the present embodiment, by connecting the dummy waveguide 36 to the dummy terminal 36a provided on the side surface 3e different from the side surface 3c and 3d provided with the common terminal 34c, The width of the vicinity of the common terminal 34c of the optical switch arrays 34a and 34b can be reduced, and the size of the entire switch unit 30 can be reduced.

(Fourth embodiment)
When optical signal path selection is performed in the optical switch 31 shown in FIG. 3, the branching ratio of the optical signal in the MZI 33 is changed by generating heat from the heater 33e of any MZI 33 included in the optical switch 31. Let At this time, heat may also propagate to the MZI 33 adjacent to the MZI 33, and the branching ratio of the MZI 33 that should not be driven may change. This phenomenon is called thermal interference. In order to prevent thermal interference, the MZIs 33 may be sufficiently separated from each other, but this causes a problem that the size of the optical switch 31 is increased. On the other hand, in the present embodiment, the arrangement of the MZI 33 is devised to suppress thermal interference and reduce the size of the optical switch 31.

  FIG. 7 is a schematic diagram showing the configuration of optical switches 31g and 31h adjacent to each other according to the present embodiment. The optical switches 31g and 31h have the same configuration as that of the optical switch 31 shown in FIG. 3, but the arrangement of the MZI 33 is different. Although the optical switches 31g and 31h adjacent to each other will be described here, the optical switches further adjacent to these may have the same configuration and arrangement.

  In the present embodiment, the arrangement of MZIs 33 'arranged on the most branch port 31b side among the plurality of MZIs 33 included in the optical switches 31g and 31h is defined. This is because the MZI 33 is densely arranged on the branch port 31b side of the optical switches 31g and 31h, and is easily affected by thermal interference. In each MZI 33 ′, of the two waveguides sandwiched between the couplers 33a and 33d, the one not provided with the heater 33e is defined as the first waveguide 33b, and the one provided with the heater 33e is defined as the second waveguide. Let it be waveguide 33c. Note that a heater 33e is provided in both the first waveguide 33b and the second waveguide 33c, and only the heater 33e provided in the second waveguide 33c is driven (heated), and the first waveguide 33b is driven. A configuration in which the heater 33e provided in the apparatus is not driven (heated) may be employed. In such a configuration, since the generation of heat is a problem in the present embodiment, the first waveguide 33b is not provided with heating means (heater 33e), and the second waveguide 33c is not provided. Is considered to be provided with heating means (heater 33e).

  In each of the optical switches 31g and 31h, the first waveguide 33b and the second waveguide 33c of the MZI 33 'adjacent to each other are configured to be alternately arranged. That is, when an MZI 33 ′ is arranged in the order of the first waveguide 33b and the second waveguide 33c in a certain direction, the MZI 33 ′ adjacent to the MZI 33 ′ has the second waveguide 33c in that direction. The first waveguide 33b is arranged in this order. Further, in the MZI 33 ′ closest to the optical switch 31h of the optical switch 31g and the MZI 33 ′ closest to the optical switch 31g of the optical switch 31h, the first waveguides 33b not provided with the heater 33e are adjacent to each other. It is configured.

  FIGS. 8A, 8B, and 8C are enlarged views of portions E, F, and G in FIG. 7, and show adjacent portions of MZI 33 '. 8A to 8C, the first waveguide 33b and the second waveguide 33c in the MZI 33 'are separated from each other by L0. L0 is a distance necessary for performing path selection by MZI by giving a predetermined optical path length difference between the two waveguides. A specific value of L0 can be obtained by experiment or computer simulation.

  FIG. 8A shows a portion where the first waveguides 33b not provided with the heater 33e are adjacent to each other in the two MZIs 33 ′ adjacent to each other in the optical switch 31g (same for 31h). They are separated by L1. On the other hand, FIG. 8B shows a portion where the second waveguides 33c provided with the heater 33e are adjacent to each other in the two MZIs 33 ′ adjacent to each other in the optical switch 31g (same for 31h). The waveguides 33c are separated from each other by L2. In FIG. 8A, since the heaters 33e are separated from each other, the heat generated by the heater 33e of one MZI 33 'hardly causes thermal interference to the other MZI 33'. In contrast, in FIG. 8B, since the heaters 33e are close to each other, the heat generated by the heater 33e of one MZI 33 'tends to cause thermal interference with the other MZI 33'. In the present embodiment, L2 is adjusted to a distance that does not cause thermal interference or is small even if any one of the heaters 33e adjacent to each other is heated, and is, for example, the same value from 80% of L0. A specific value of L2 can be obtained by experiment or computer simulation. L1 is smaller than L2 and is a value equal to or greater than a predetermined distance (for example, 15 μm) at which coupling between the waveguides does not occur. In addition, since a plurality of paths are not transmitted simultaneously in one optical switch 31g (the same applies to 31h), heaters e of MZI 33 'adjacent to each other are not driven simultaneously. Therefore, even if some thermal interference occurs in the adjacent MZI 33 ′ by the MZI 33 ′ in which the heater 33e is driven by reducing L1, the MZI 33 ′ in which the heater 33e is not driven will quench the optical signal. Therefore, the influence on the extinction characteristic is small.

  FIG. 8C shows a portion where the optical switches 31g and 31h are adjacent to each other, and the first waveguides 33b are separated from each other by L3. As described above, in FIG. 8A, the heaters 33e of the MZIs 33 'adjacent to each other in one optical switch are not simultaneously driven, so that the first waveguides 33b can be brought close to each other. 8C is an adjacent portion between the optical switch 31g and the optical switch 31h that operate independently, and therefore, the heater 33e of the MZI 33 ′ of the optical switch 31g and the heater 33e of the MZI 33 ′ of the optical switch 31h. May be heated at the same time. For this reason, if they are brought close to each other as shown in FIG. Further, the MZI 33 'in which the heater 33e is heated is controlled so as to transmit an optical signal, and even a slight thermal interference has a significant effect on the transmission characteristics. In the present embodiment, L3 is adjusted to a distance that does not cause thermal interference or is small even if the heaters 33e of the two MZIs 33 'are simultaneously heated, and is, for example, about 80% of L0. L3 is larger than L1. A specific value of L3 can be obtained by experiment or computer simulation.

  As described above, in each of the optical switches 31g and 31h according to the present embodiment, the distance between the waveguides 33c provided with the heaters 33e adjacent to each other is the first distance that can suppress thermal interference. , Thermal interference can be suppressed. At the same time, since the distance between the waveguides 33b not provided with the heaters 33e adjacent to each other is set to a second distance smaller than the first distance, the sizes of the optical switches 31g and 31h are reduced. Can do. Further, since the distance between the waveguides 33b adjacent to the optical switch 31g and the optical switch 31h is the third distance that can suppress the thermal interference, the thermal interference between the adjacent optical switches 31g and 31h is also suppressed. can do.

  The optical switches 31g and 31h according to the present embodiment can be used for any of the switch unit 30 and the split switch unit 30a according to the first to third embodiments.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, in each of the above-described embodiments, the switch device including 16 1 × 16 optical splitters and 32 8 × 1 optical switches is shown, but the present invention is not limited to this. The number of optical splitters and optical switches on one chip is also arbitrary. A person skilled in the art can use an optical splitter and an optical switch having a necessary number of branches according to the number of paths and the number of wavelengths to which the switch device corresponds, and arrange them in the required number as in the above-described embodiment. Good.

Claims (10)

A switch unit for selecting and outputting a path of an input optical signal,
A substrate,
One common port for inputting and outputting the optical signal, a plurality of branch ports for inputting and outputting the optical signal, a plurality of waveguides connecting the common port and the branch port, First and second optical switch arrays each having a plurality of Mach-Zehnder interferometers (MZI) provided on the waveguide, each comprising an optical switch extending along the surface of the substrate;
With
The first and second optical switch arrays have a tapered shape from the branch port side toward the common port side,
The first optical switch array such that the branch port of the optical switch included in the first optical switch array and the common port of the optical switch included in the second optical switch array are close to each other; A switch unit comprising the second optical switch array .   The common port of the optical switch included in the first optical switch array and the branch port of the optical switch included in the second optical switch array are connected to a first side surface of the substrate, and the first The second side surface of the substrate in which the branch port of the optical switch included in one optical switch array and the common port of the optical switch included in the second optical switch array are opposed to the first side surface. The switch unit according to claim 1, wherein the switch unit is connected to the switch unit. The optical switch further includes a dummy waveguide connected to the branch port and not connected to the common port;
The switch unit according to claim 2, wherein the dummy waveguide is connected to a third side surface of the substrate different from the first side surface and the second side surface. The first optical switch array includes a plurality of the optical switches in which the common ports are arranged in parallel and the branch ports are arranged in parallel.
The second optical switch array includes a plurality of the optical switches in which the common ports are arranged in parallel and the branch ports are arranged in parallel. The switch part of any one of -3. The first and second optical switch arrays have a substantially right triangle shape having a bottom side on the branch port side and sandwiched between a hypotenuse and a perpendicular side from the branch port side toward the common port side. Have
The first optical switch array and the second optical switch array are arranged so that the oblique side of the first optical switch array and the oblique side of the second optical switch array are close to each other. switch unit according to any one of claims 1-4, characterized in. The substrate can be of any claim 1-5, characterized in that it is divided into a first substrate including a first optical switch array, and a second substrate including the second optical switch array Or the switch part according to 1. A first electrode pad provided on a side opposite to the second optical switch array with respect to the first optical switch array and connected to the optical switch included in the first optical switch array;
A second electrode pad provided on the opposite side of the first optical switch array with respect to the second optical switch array and connected to the optical switch included in the second optical switch array;
Switch unit according to any one of claims 1-6, characterized in that it further comprises a. The MZI has a first waveguide that is not heated and a second waveguide that is heated;
In the optical switches included in each of the first and second optical switch arrays, a first distance between the first waveguides adjacent to each other is a second distance between the second waveguides adjacent to each other. switch unit according to any one of claims 1-7, characterized in that the smaller than the distance. The first waveguide of the first optical switch array closest to the second optical switch array and the first waveguide of the second optical switch array closest to the first optical switch array The switch unit according to claim 8 , wherein a third distance between and is greater than the first distance. The switch part according to any one of claims 1 to 9 ,
A splitter for splitting or merging the optical signals;
An optical fiber connecting the switch unit and the splitter unit;
A switch device comprising:

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